The “10,000 hour rule” – the idea that 10,000 hours of practice is the amount needed to excel in an activity, as described in Malcolm Gladwell’s 2008 book Outliers – has been getting more attention than usual recently. The attention is partly because of the release of Gladwell’s new book, David and Goliath, but it’s also because of the discussion of the rule in another new book –  The Sports Gene, by former Sports Illustrated senior writer David Epstein. In his investigation of what leads to outstanding athletic performance, Epstein points out some contradictions to Gladwell’s rule – for example, that athletes at the same level of competition can have very different amounts of practice time or playing experience, and that success in sports isn’t determined only by how much an athlete practices.

A few weeks ago, in this article in the New Yorker, Gladwell responded to Epstein and to other critics of the “10,000 hour rule”.  Since I’ve written a blog post about Gladwell’s misinterpretations of the research cited in Outliers in support of the rule, I was very interested in what Gladwell had to say. But it seems that the article is full of the same kind of selective reading and irrelevant information that were problematic in Outliers’ original discussion of the rule.

Gladwell’s New Yorker article opens with this statement:

Forty years ago, in a paper in American Scientist, Herbert Simon and William Chase drew one of the most famous conclusions in the study of expertise…’We would estimate, very roughly, that a master has spent perhaps 10,000 to 50,000 hours staring at chess positions’.

Here is the full text of Simon and Chase’s article – and from the full text, it’s obvious that Gladwell’s characterization of Simon and Chase’s finding as a “famous conclusion” is misleading, at best. Simon and Chase’s study investigated how experienced chess players learn to recognize patterns of chess pieces’ positions on the chessboard, and then how they memorize, select and use game strategies based on those perceptions. The “10,000 to 50,000 hours” statement is a contextual statement, used only to give a broad sense of how long it takes top-level chess players to be able to recognize many different chessboard patterns. Simon and Chase acknowledge, as Gladwell does, that “thousands of hours of practice” are needed to acquire high-level skills – but the “10,000 to 50,000 hour” number is not supported by any data. And, notably, the authors’ own description of the number includes the words “very roughly” and “estimate”. They do not label it as a “conclusion”,  nor do they present it as one.

Gladwell then continues, “In the years that followed, an entire field within psychology grew up devoted to elaborating on Simon and Chase’s observation”. Simon and Chase identified a lot of practice as being important to mastering an activity, and that finding has been well researched in psychology and in other disciplines – but if the “observation” is the “10,000 to 50,000 hour” number, then Gladwell’s statement is incorrect. Simon and Chase’s article is “famous” in the sense that it has been widely referenced in other research – Google Scholar shows it has been cited in over 800 other research publications – but these articles are not “elaborating” on the “10,000 to 50,000 hour” estimate. Most of these articles build on Simon and Chase’s findings about skill development, problem solving, memory, and/or decision-making. They are not investigating the specific number of practice hours needed for expertise.

As an example of the research in this alleged “field”, Gladwell cites a paper by John Hayes on the careers of great composers. The paper itself isn’t available online, but its contents are described in this article. Hayes’ paper, as the title indicates, looks at patterns of creative output across the lifespan of composers’ careers – but not at how many hours of practice the composers needed to develop the expertise to produce that output. So it’s difficult to see how this research can be described as “elaborating” on Simon and Chase’s “observation”.

Gladwell claims that “this is the scholarly tradition” he referenced in Outliers when writing about the 10,000 hour rule. It’s true that there’s a lot of research devoted to understanding how people become elite performers or develop high levels of expertise, and to ascertaining the effects of practice or training on skill development. And that’s not surprising, because these are fascinating questions, and the answers would have a great deal of practical applicability. But Gladwell ignores the reality that there is no body of published research establishing 10,000 hours as “the magic number of greatness”, as he stated in Outliers. He also doesn’t acknowledge that some of the scholars whose work he cited in Outliers have criticized his interpretations of their research; K. Anders Ericsson, whose work Gladwell extensively cited as supporting the “10,000 hour rule”, has called Gladwell’s rule a “provocative generalization”. To describe the “10,000 hour rule” as being based in a “scholarly tradition” gives the rule an academic authority that is unwarranted.

To counteract Epstein’s points about elite performers having a range of variation in their amounts of practice time, Gladwell cites a recent paper by Robert Howard on skill acquisition by chess players. Howard has published several papers on this topic, but Gladwell appears to be referring to this one. The data presented in the paper show, as Gladwell says, that two of the three chess-playing Polgar sisters put in over 50,000 hours of practice to achieve their highest player rankings, and that eight chess players who achieved the rank of grandmaster put in approximately 14,000 hours of practice each. But Howard also says very clearly in the abstract of the paper:

Performance differences among the sisters cannot be accounted for by practice differences…[T]wo sisters reached peak performance levels comparable to those of many far less-practiced players entering the international domain around the same time[.]

Rather than supporting Gladwell`s point about a lot of practice being important, this statement seems to more strongly support Epstein’s point about different amounts of practice all having the potential to improve performance to similar levels. And in another paper, Howard makes some important observations about the difficulty of accurately measuring hours and types of practice – a difficulty that Gladwell has never really addressed:

Deliberate practice may be measurable objectively in principle but is difficult to gauge over years in naturalistic studies. Researchers often just ask participants to estimate their practice hours. Such data may be useful when backed up with diary entries and parental reports, but memory is notoriously unreliable and estimates may be quite inaccurate. Furthermore, all deliberate practice hours cannot be equal. An hour spent carefully studying a good chess manual must help expertise development more than one spent inattentively leafing through a bad manual.

Gladwell then moves on to discuss when the “10,000 hour rule” is applicable and when it isn’t. It’s encouraging that he makes a distinction, because other writers have pointed out that in some activities it would be very difficult to put in 10,000 hours of practice no matter how dedicated or talented you were. However, Gladwell’s distinction appears to be that the rule doesn’t apply to “cognitively complex” activities – “instances where there are not a long list of situations and scenarios and possibilities to master”. His examples of these types of activities are high jumping, sprinting, and playing darts. How are these not “cognitively complex”? The basic actions at the center of each of these activities – jumping, running, throwing – may be relatively simple, but to be good at any of them requires making multiple strategic decisions and then being able to execute them correctly: e.g. a high jumper has to choose the optimal speed and angle for the approach to the bar, and the best body position and timing for the jump. And I also have to wonder why, if the 10,000 hour rule doesn’t apply to every activity, Gladwell didn’t mention that more prominently in Outliers.

On a larger level, though, it’s frustrating to me as a researcher that the problems with Gladwell’s reporting of the studies he cites – both in Outliers and in the New Yorker article – are not problems of comprehending obscure or complex concepts. Anyone who understands basic principles of research design, data analysis, and presentation of experimental results – all skills that Gladwell certainly should have acquired by now – should be able to look at any one of these articles and accurately identify what the experiments are testing and what the results are saying.

And it’s also frustrating that Gladwell’s New Yorker article seems to blame misunderstandings of the 10,000 hour rule on anyone other than himself. He states that “some of the critiques are just bewildering”, and cites this Time magazine article as an example. Gladwell disputes the Time article’s statement that 10,000 hours of practice would lead to success “regardless of a person’s natural aptitude” – and he’s right that he didn`t say that in Outliers. But it wasn’t Time, or David Epstein, or K. Anders Ericsson, or Robert Howard, or John Hayes, or Herbert Simon and William Chase who asserted that “[t]en thousand hours is the magic number of greatness”.  It was Gladwell who said that, and it was Gladwell who labeled 10,000 hours as a “rule”. It would be refreshing if he would take some responsibility for that.